1. Field of the Invention
The present invention relates generally to a fiber optic distribution cable and, more particularly, to a factory assembled fiber optic distribution cable having at least one predetermined access location for providing access to at least one preterminated and pre-connectorized optical fiber.
2. Description of the Related Art
Optical fibers are used for a variety of applications including voice communication, data transmission and the like. With the ever-increasing need for connecting remote locations to a fiber optic distribution cable, it is apparent that more efficient methods of performing a mid-span access of a distribution cable are required. Typically, to perform a mid-span access, a technician must remove a portion of the cable sheath in the field at a convenient location along an installed distribution cable. Once the sheath is removed, the technician must access pre-selected optical fibers, sever the pre-selected optical fibers and remove a length of the optical fibers from the distribution cable. The removed length of optical fiber provides the field technician with adequate length to splice one or more optical fibers of a cable comprising a lesser amount of optical fibers than the distribution cable, typically termed a “drop cable,” to the distribution cable optical fibers. After all splicing is complete, the accessed location is typically covered using an enclosure designed to protect the splices and the section of the distribution cable with the sheath removed. This time consuming process is typically accomplished by a highly skilled field technician at a significant cost and under field working conditions.
Several approaches have been developed to overcome the disadvantages of accessing optical fibers in the field. In one approach, the splicing of drop cables to the distribution cable is performed at a factory during the manufacturing of the cable. The preterminated cable, including the main cable, drop cables and associated splice closures, are assembled and wound onto a cable reel to be delivered to an installation site. Accordingly, conditions for making high quality splices may be maximized in the factory, thereby increasing splice quality and also reducing the expense and difficulty associated with field splicing.
U.S. Pat. No. 5,121,458 (the '458 patent) issued to Nilsson et al. and entitled “Preterminated Fiber Optic Cable,” describes a preterminated fiber optic cable having a main trunk cable comprising a plurality of optical fibers disposed therein, and multiple drop cables spliced to the trunk cable at various branch points. The preterminated fiber optic cable is assembled at the time of manufacture and is installed thereafter. At each branch point, a splice closure is utilized for protecting the optical fibers and splices from moisture and mechanical damage, providing a strong anchoring point for the optical fiber drop cable and insuring that the minimum fiber bend radius is not violated. While the preterminated fiber optic cable assembly described in the Nilsson et al. patent is useful in certain applications, its use is limited to applications in which it is installed through a conduit having an outer diameter of about 4 inches or greater. In addition, the relatively large outer diameter of the splice closure greatly hinders winding the assembled cable onto a cable reel.
U.S. Pat. No. 5,528,718 (the '718 patent) issued to Ray et al. and entitled “Fiber Optic Cable System Including Main and Drop Cables and Associated Fabrication Method,” describes an approach for reducing the size of the branching point of the drop cables from the main cable. The cable system is assembled in the factory and includes a main cable and one or more drop cables connected to the main cable at spaced apart locations along the main cable. The drop cable is spliced to the main cable using a splice closure including a fiber guide that secures spliced together end portions of the respective optical fibers in a longitudinally extending direction and devoid of any slack coils of optical fiber. Accordingly, the overall diameter of the splice closure is reduced in size as compared to the splice closure of the Nilsson et al. patent, thereby permitting the cable system to be stored on a reel and to be readily installed through a conduit. A disadvantage of this system is that the outer diameter of the assembly exceeds the inner diameter of the conduit through which the cable system is typically installed within when multiple drop cables are connected at a single branch point.
Accordingly, there continues to be an unresolved need for a factory assembled, preterminated and pre-connectorized distribution cable that reduces field installation costs and has an outer diameter that does not exceed the inner diameter of the conduit through which the cable system is typically installed. As such, it is desirable to provide a pre-connectorized fiber optic distribution cable including one or more predetermined access locations having factory preterminated and pre-connectorized optical fibers along the length of the distribution cable. Further, it is be desirable to provide a pre-connectorized fiber-optic distribution cable having the lowest possible profile, while still maintaining discrete fiber capability. It is also desirable in a fiber-to-the-premises (FTTP) optical network to provide a pre-connectorized access location in the mid-span of a distribution cable that is adapted to be readily deployed in the field with temporary protective components that are easily removed so that a permanent protective closure may be added to the cable.